In today's information age, computer and communication systems often require large amounts of data storage. More and more frequently, access to data storage is being provided over communication networks. Among other things, this makes data storage resources available to a number of data storage users.
FIG. 1 shows a conceptual view of a storage system 106 that is accessed by a number of users 102 over a communication network 104, such as an Ethernet local area network (LAN), as is known in the art. The users 102 represent various entities that access storage services provided by the storage system 106 over the communication network 104. The users 102 can be inside or outside of the storage system 106 (for example, as will be discussed below, a server within the storage system 106 may provide storage services as well as access storage services over the communication network 104).
There are generally two types of network-based data storage technologies that are used in the storage system 106, namely Storage Area Network (SAN) and Network-attached Storage (NAS). SAN is traditionally defined as the provision of raw block data using a Fibre Channel (FC) network. NAS typically provides file services over the LAN 104.
FIG. 2 shows a SAN-based storage system as is known in the art. The SAN-based storage system includes a number of storage devices 210 in communication with a number of servers 206 over a FC network 208. The FC network 208 and the storage devices 210 represent a SAN, and the servers 206 are essentially users of the SAN. Each of the servers 206 typically supports a particular application. For example, there may be separate servers for email and World Wide Web applications. The storage resources provided by the storage devices 210 are typically partitioned, and a separate portion of the storage resources is allotted to each server 206 for a particular application. Each of the servers 206 is only permitted to access that portion of the storage resources it is allotted. Each of the servers 206 is coupled to the LAN 104. Among other things, the LAN 104 allows for inter-server communication (for example, to allow for file sharing between different applications and for copying data from one application to another) and also for access to the servers 206 by the users 102.
FIG. 3 shows an exemplary NAS-based storage system as is known in the art. The NAS-based storage system includes a NAS server 306 in communication with a number of dedicated storage devices 310, for example, over a FC network 308. The NAS server 306 manages and controls the dedicated storage devices 310 so as to allow multiple applications to share the storage resources at a file level, rather than dedicating portions of the storage resources to specific applications, as in a SAN. Thus, the NAS server 306 provides multi-user access to storage resources at a file level and also provides for capacity sharing by making all storage resources available to all applications if needed or desired. The NAS server 306 is coupled to the LAN 104. Among other things, the LAN 104 allows for access to the NAS server 306 by the users 102.
SAN and NAS are not mutually exclusive technologies. For example, as shown in FIG. 3, the FC network 308 and the dedicated storage devices 310 are essentially a SAN that is managed and controlled by the NAS server 306. Also, as shown in FIG. 4, the storage system 106 may include both SAN and NAS technologies, with the servers 206 and the NAS server 306 coupled to the LAN 104.
One problem with the SAN-based storage system, as discussed with reference to FIG. 2 above, is that inter-server data transfers (such as file sharing between different applications and copying data from one application to another) are made over the LAN 104. This can have a serious impact on overall system performance, both by increasing the traffic load on the LAN 104 and by increasing the processing load on the servers 206. In a NAS-based storage system, such file sharing and data copying can be accomplished by the NAS server 306 without using the LAN 104, so such operations have little or no impact on overall system performance.